That's the arterial circulation.
What about veins?
Oh my god,
there are veins in the heart.
Yeah, there are,
that's how we get blood back
from the muscle of the heart
back into the venous circulation.
So how does this happen?
Well, so there are variety of veins
that more or less follow the arteries.
They all collect into
the great cardiac vein,
which wraps around
the back of the heart.
And then that dumps all of its
contents into the coronary sinus,
which enters into
the right atrium.
So this is kind of shown here,
in a slightly different view,
you can see the blood coming from that
great cardiac vein into the coronary sinus,
and that's dumping into the right
atrium just above the tricuspid valve.
Okay, again, kind of talked about it,
we're berating this point,
because it's really important, there is
a collateral circulation in the heart.
So this is our right
our left anterior descending
artery, our left circumflex artery,
and there are zones between them
where there's collateralization,
that allows making sure that we can get
blood supply to all parts of the heart.
We already talked about the collaterals
that will happen at the apex.
And we talked about those that would happen
between the right posterior circulation
and the left
Okay, if we cut the heart
in that transverse slice,
this is generally how the parts of the
heart are being perfused in 90% of us.
Keep in mind this will be different if
you have a left dominant circulation.
So the anterior 2/3 of the
septum in the anterior wall
and beginning into the lateral
wall, all of that in purple there
is perfused by the left
anterior descending circulation.
On the lateral wall, indicated here in
green is the left circumflex circulation,
the entire right ventricle and
the posterior left ventricle
and posterior 1/3 of the septum
is perfused in general by the
right coronary circulation.
So knowing this anatomy,
you can predict which parts of
the heart are going to be affected
if there's blockage, major blockage in
one of the vessels perfusing that area.
On this slide, we are going to look
at many of the valvular structures
and their relationships
one to another.
By the time we finish with this slide,
there are going to be words all over it.
But we're going to do it step by step,
so you'll be able to follow along.
We're going to follow the way that
blood flows through the heart.
So we're going to begin in
the upper left hand corner.
That's what the tricuspid valve.
Blood is coming from the
inferior and superior vena cava,
into the right atrium.
The right atrium is then
going to push the blood
into the right ventricle
through the tricuspid valve.
It is a trileaflet there are three
leaflets of the tricuspid valve,
a posterior leaflet,
a septal leaflet and an anterior leaflet.
Just above that is where we're going
to have the coronary sinus come in.
Okay, so that gets you oriented to where we
are in terms of the geography of the heart.
Okay, that's going
to allow blood to go
from the right atrium
of the right ventricle.
From the right ventricle
out to the lungs
is the pulmonary valve.
The pulmonary valve, again, remember sits
at the most anterior portion of the heart.
It has a tricuspid, three cusps
valve, it's a semi lunar valve,
we'll talk more about semilunar
versus atrioventricular valves,
that goes out to the lungs
gets oxygenated all the blood comes back
through from the left to the left atrium.
And then between the left atrium left
ventricle is going to be the mitral valve
in the upper right hand corner.
It's got just two leaflets.
It's got a posterior leaflet
and an anterior leaflet.
Okay, so it has a slightly different
structure than the other valves
which have usually three
cusps, or three leaflets.
That's actually why the mitral
valve is more prone to more diseases
than any of the other valves.
Interesting little factoid.
Okay, so we have a posterior and
anterior leaflet of the mitral valve,
blood gets into
the left ventricle,
and then get squeezed out
through the aortic valve.
And the aortic valve again, normally
is a three cusp valve, three cusps,
and they have an anterior,
we have a posterior non coronary cusp.
We have an anterior coronary cusp that has
the right coronary artery coming off it
and the left anterior coronary cusp
that has the left main coming off it.
So the areas behind those cusps
are called the sinuses of Valsalva.
Alright, we've covered all
the words on this slide.
Let's look at these in a
little bit more detail.
Okay, the way that the valves
work are a little bit different
depending on whether you
are a semilunar valve
that is to say pulmonic
or aortic valve,
versus whether you are a
tricuspid or a mitral valve,
an atrioventricular valve.
So, let's look at
the tricuspid valve
and everything I'm going to
say about the tricuspid valve
is also true about
the mitral valve.
These are the
they are the entry points from
the atrium to the ventricles.
The valves are dependent on
the integrity of the annulus.
The ring that holds
the valve tissue,
it's dependent on the integrity
of the valve leaflets themselves.
It's dependent on the
chordae tendineae shown here,
so thin, delicate,
that connect to the
edge of the valve
to the underlying
Papillary muscles contiguous
with the right ventricular wall.
All elements of the
whether your tricuspid
or mitral must be intact
in order for that valve
to maintain competence.
Mitral valve, same story.
again, mitral valve,
the integrity of the
annulus is important.
The integrity the
the actual leaflets, important.
The integrity of the chordae
The integrity of the papillary
Integrity of the ventricular
And we will talk when we talk about
valvular pathology in a subsequent talk,
how the ventricular wall may
dilate, may get expanded,
and when it does it pulls
on the papillary muscles
which pull in the chordae tendineae which
keep the valves from being able to close.
So simply having a
chamber that is abnormal,
in terms of its dilation can lead
to valvular dysfunction as well.
Okay, those are
We'll talk briefly about the conduction
system and we'll come back to this.
So the heart is a
it's got all these various elements
that you need to be aware of,
because there's pathology
associated with all of them.
One of the beautiful elements
of this is a self-beating,
self-regulating tissue that
has a certain conduction system
that allows it to contract in an
organized fashion to pump blood.
The initial signal that says go or
no go is at the sinoatrial node.
And it's followed by activation
signal at the atrioventricular node.
We'll revisit this,
we'll get in more detail in a moment.
Let's look at all the
elements of the heart in turn.
So we're gonna have the myocardium,
we're gonna have the valves,
we're gonna have the coronary vasculature,
we're gonna have the conduction system,
and all of them have to work together
for the heart to do its thing,
which it's doing there very
nicely on the left hand side,
it's beating in an organized
fashion to pump blood
in an organized fashion at a particular
pressure to the rest of the body.
so myocardium works fine here,
the valves work fine,
the coronary vasculature is fine,
but what's wrong here is that we
have an abnormal conduction system.
And what's being shown in
particular is atrial fibrillation.
See that right atrium, left atrium,
it's just kind of quivering,
it's not doing its thing,
because there's not a
good regular conduction
from the sinoatrial
node to the AV node.
AV node then fires every now and
then when a signal gets through.
So you have an
So instead being bump,
bump, bump, bump,
it's bump, bump, bump,
bump, bump, bump, bump bump.
And that's because of
the atrial fibrillation.
We will talk more about how that happens
in a subsequent discussion you and I.
So atrial fibrillation,
in most cases can be tolerated.
Ventricular fibrillation is what
happens just before you die.
So instead of having a
nice contractile function,
providing blood supply to the entire body,
including the brain, kidney, and liver,
and all those other
Now the heart is quivering.
So there is no longer a
there's no longer
And with about 1-2 minutes
of this fibrillation,
there's not any perfusion to the brain and
the brain checks out and you formally die.
So V-fib (ventricular
fibrillation) is a lethal rhythm.